IUDs, Implants are Most Effective Birth Control (video) Washington University School of Medicine Share Print E-Mail Loading video... Caption A study to evaluate birth control methods has found dramatic differences in their effectiveness. Women who used birth control pills, the patch or vaginal ring were 20 times more likely to have an unintended pregnancy than those who used longer-acting forms such as an intrauterine device (IUD) or implant. Results of the study, by researchers at Washington University School of Medicine in St. Louis, are reported May 24 in the New England Journal of Medicine. Credit Washington University in St. Louis Usage Restrictions Please note embargo: 5 PM EDT, Wednesday, May 23, 2012 Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.